AB1322 APPENDICITIS STILL A MISDIAGNOSIS FOR FMF PATIENTS
Authors: S. N. Baspinar, A. Alkan, M. B. Yuzbasioglu, S. Yenigun, A. Y. Ayla, I. Durucan, M. Candan, A. Karabicek, C. Belli, T. Bayraktar, H. Ozdogan, S. Ugurlu
Journal: Annals of the Rheumatic Diseases (2022)

Background Familial Mediterranean Fever(FMF) is an autoinflammatory disease characterized by recurrent polyserositis attacks. Attacks typically consist of fever and/or abdominal pain and/or chest pain and/or arthritis. The disease is caused by mutations in the MEFV gene. Abdominal pain during the attacks is frequently misdiagnosed as acute abdomen and these patients go undersurgical intervention is not uncommon [1]. Objectives Severe abdominal pain during FMF attacks is frequently misdiagnosed as acute abdomen and patients receive surgical intervention. In this study, we aim to compare the clinical and genetic characteristics of FMF patients with appendectomies to those without appendectomies. Methods We reviewed 176 patients with FMF who went under appendectomy. We randomly matched these patients with 176 FMF patients without appendectomy for comparison. We compared clinical manifestations, MEFV mutations, and treatment modalities. Results In this study, 176 patients with FMF went under appendectomy. Only 2 of these appendectomies were performed after FMF diagnosis. In the appendectomy group fever(84% vs 68%), abdominal pain(91% vs 79%), pathogenic exon 10 mutations(65% vs 59%), lower leg pain(0.5% vs 0%) and orchitis(0.5% vs 0%) were more common but only the abdominal pain and fever was statistically significant. In the control group chest pain(18% vs 19%), arthralgia(46% vs 53%), arthritis(29% vs 37%), anti IL-1 usage(3% vs 5%), amyloidosis (0% vs 3%) and erysipelas(1% vs 3%) were more common but none of them were statistically significant. Myalgia(3%) was the same in both groups[Table 1]. Median diagnostic delay was 8(IQR 2-15) years in the appendectomy group and 3.5(IQR1-10) years in the control group. Table 1. Characteristics of the patients No Of Patients(%)Appendicitis No Of Patients(% ) P value Control Group Patients 176(100) 176(100) Fever 148(84) 120(68) 0.0007 Abdominal Pain 160(91) 139(79) 0.0029 Chest Pain 32(18) 33(19) 1 Arthralgia 81(46) 94(53) 0.20 Arthritis 51(29) 65(37) 0.12 Myalgia 5(3) 5(3) 1 Erysipelas 2(1) 5(3) 0.45 Lower Leg Pain 1(0.5) 0(0) - Orchitis 1(0.5) 0(0) - Anti IL-1 usage 6(3) 9(5) 0.6 Amyloidosis 0(0) 6(3) - Diagnostic Delay 8.5(IQR2-15) years 3.5(IQR1-10) years 0.0002 Pathogenic Exon 10 Mutations 114(65) 103(59) 0.27 Appendectomy Before FMF diagnosis 174(99) 0(0) Conclusion Even after the discovery of colchicine and identification of the MEFV gene diagnosis of FMF remains a challenge. Previous studies reported a median diagnostic delay of 8.2-11 years. In these studies, 28%-32% of the patients went under abdominal surgical intervention before the diagnosis of the FMF[2,3]. The most common symptoms of FMF(fever and abdominal pain) are also the most common symptoms of acute abdomen. Thus distinguishing between FMF and acute abdomen in undiagnosed FMF patients represents an understated problem. These patients have a longer diagnostic delay[8(IQR 2-15) vs 3.5(IQR1-10) years], worse control of attacks, poorer quality of life. In our study, most of the appendectomies were unnecessary in the FMF patients. Thus we recommend investigating the patient for FMF if the evidence of the acute abdomen does not expand beyond the symptoms. References [1]Ozdogan H, Ugurlu S. Familial Mediterranean Fever. Presse Med. 2019 Feb;48(1 Pt 2):e61-e76. [2]Erdogan M, Ugurlu S, Ozdogan H, Seyahi E. Familial Mediterranean fever: misdiagnosis and diagnostic delay in Turkey. Clin Exp Rheumatol. 2019 Nov-Dec;37 Suppl 121(6):119-124. [3]Hageman IMG, Visser H, Veenstra J, Baas F, Siegert CEH. Familial Mediterranean Fever (FMF): a single centre retrospective study in Amsterdam. Disclosure of Interests None declared